fix(youtube): use url= param for ScrapeCreators comments/transcript + parse new response shape (#265)

PR #260 wired YouTube comment enrichment against
`/v1/youtube/video/comments` with `id=<video_id>`, but the endpoint
requires `url=https://www.youtube.com/watch?v=<video_id>`. Every enrich
call was returning 400 "missing_parameter: you must provide a url", so
no YouTube items ever carried `top_comments`.

The SC transcript fallback (`_sc_fetch_transcript`) had the identical
contract mistake. It was latent because `_fetch_transcript` prefers
yt-dlp and the SC path only fires when yt-dlp is missing, but it would
have failed the same way on hosts without yt-dlp installed.

Switching both callers to `url=` surfaces a second issue in the
response parser: SC returns `author` as `{"name": "@handle", ...}` and
nests like counts under `engagement.likes`, not top-level. The parser
was reading `author` as a string and missing the nested likes, so even
after the param fix every comment would land with an object-shaped
author and 0 likes.

- `_fetch_video_comments`: send `url=` on both urllib and requests branches
- `_sc_fetch_transcript`: same
- Response parser: extract `author.name` when author is a dict, read
  `engagement.likes` when top-level `likes` is absent, prefer
  `publishedTime` / `publishedTimeText` for date. Legacy string-author
  and top-level-likes shapes still work, so existing mocks are unchanged.

Verified live against api.scrapecreators.com: `_fetch_video_comments`
now returns fully-populated comments with real @handles and like
counts (e.g. "@JennyNicholson: ... (49000 likes, 2025-04-15)"). All
tests in youtube_yt/normalize/signals/render pass.

Plan: docs/plans/2026-04-15-002-fix-youtube-comments-scrapecreators-param-plan.md

🤖 Generated with Claude Opus 4.6 (1M context) via [Claude Code](https://claude.com/claude-code) + Compound Engineering v2.56.1

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/lib/youtube_yt.py

@@ -732,10 +732,11 @@ def _fetch_video_comments(
     Returns:
         List of comment dicts with author, text, likes, date.
     """
+    video_url = f"https://www.youtube.com/watch?v={video_id}"
     if not _requests:
         try:
             from urllib.parse import urlencode
-            params = urlencode({"id": video_id})
+            params = urlencode({"url": video_url})
             url = f"{SCRAPECREATORS_YT_BASE}/video/comments?{params}"
             headers = http.scrapecreators_headers(token)
             headers["User-Agent"] = http.USER_AGENT
@@ -747,7 +748,7 @@ def _fetch_video_comments(
         try:
             resp = _requests.get(
                 f"{SCRAPECREATORS_YT_BASE}/video/comments",
-                params={"id": video_id},
+                params={"url": video_url},
                 headers=http.scrapecreators_headers(token),
                 timeout=30,
             )
@@ -763,11 +764,32 @@ def _fetch_video_comments(
         text = c.get("text") or c.get("body") or c.get("content", "")
         if not text:
             continue
+
+        # SC returns author as {"name": "@handle", ...}; legacy mocks may pass a string.
+        author = c.get("author") or c.get("author_name", "")
+        if isinstance(author, dict):
+            author = author.get("name") or author.get("handle") or ""
+
+        # SC nests likes under engagement.likes; legacy shapes used top-level keys.
+        engagement = c.get("engagement") or {}
+        likes = c.get("likes")
+        if likes is None:
+            likes = engagement.get("likes", 0) if isinstance(engagement, dict) else 0
+        if not likes:
+            likes = c.get("vote_count", 0)
+
+        date = (
+            c.get("date")
+            or c.get("published_at")
+            or c.get("publishedTime")
+            or c.get("publishedTimeText", "")
+        )
+
         comments.append({
-            "author": c.get("author") or c.get("author_name", ""),
+            "author": author,
             "text": text[:400],
-            "likes": c.get("likes") or c.get("vote_count", 0),
-            "date": c.get("date") or c.get("published_at", ""),
+            "likes": likes,
+            "date": date,
         })
 
     return comments
@@ -931,10 +953,11 @@ def _sc_fetch_transcript(video_id: str, token: str) -> Optional[str]:
     Returns:
         Plaintext transcript string, or None if unavailable.
     """
+    video_url = f"https://www.youtube.com/watch?v={video_id}"
     if not _requests:
         try:
             from urllib.parse import urlencode
-            params = urlencode({"id": video_id})
+            params = urlencode({"url": video_url})
             url = f"{SCRAPECREATORS_YT_BASE}/video/transcript?{params}"
             headers = http.scrapecreators_headers(token)
             headers["User-Agent"] = http.USER_AGENT
@@ -946,7 +969,7 @@ def _sc_fetch_transcript(video_id: str, token: str) -> Optional[str]:
         try:
             resp = _requests.get(
                 f"{SCRAPECREATORS_YT_BASE}/video/transcript",
-                params={"id": video_id},
+                params={"url": video_url},
                 headers=http.scrapecreators_headers(token),
                 timeout=30,
             )